This invention relates to joint assemblies for electrical busway apparatus.
Electrical busway is utilized to conduct low voltage, high current power between a source and the controls for the ultimate load apparatus. A typical busway system includes a number of lengths of bus duct connected together end-to-end, each bus duct comprising a housing containing a plurality of bus bars and a connection joint at one end.
In present day busway systems, considerable emphasis has been placed on joint design to facilitate mechanical connection and provide good electrical connection. An exemplary busway joint is disclosed in U.S. Pat. No. 3,786,394, issued on Jan. 15, 1974 to Martin F. Koenig et al and assigned to the assignee of this application. As shown therein, a joint comprising a stacked assembly of insulators and electrical splice plates is disposed on the end of one length of bus duct such that pairs of splice plates are positioned on opposite surfaces of the respective bus bars and insulator plates are provided on the outer side of the assembly and between adjacent splice plates associated with different bus bars. A single, insulated bolt extends through the entire assembly, and loosely secures the joint to said one bus duct. Interfitting hook means are provided between the bus bars and splice plates to retain the joint to the bus duct even when loosely assembled. In installation, a second bus duct is inserted into the other side of the loose joint assembly such that the bus bars thereof are disposed between the respective pairs of splice plates. The connection is completed by tightening the bolt to compress all of the elements of the joint together, particularly the splice plates upon the opposite surfaces of the bus bars. To obtain the desired electrical conduction properties, such joints require compressive pressures which in turn require a torque to be applied to the bolt on the order of 75 foot pounds.
The present invention relates to an improvement in the above described busway joint. It provides a joint which is rigidly secured to the first bus duct at the point of manufacture to provide a rigid receptacle into which the second bus duct may be plugged-in during installation. This construction requires no subsequent tightening of the bolt by the installer. In addition, an enhanced electrical connection is provided.